1. Field of the invention
The present invention relates to structure of a miniature pumping machinery, and more particularly, to a miniature diaphragm pump in which an air flow route is appropriately governed to stabilize the air flow rate.
2. Description of the prior art
A general function of a conventional miniature pumping machinery is either simply outputting compressed air, or repeatedly performing the action of inhaling/exhausting air at a stationary position. An ordinary check valve is required for maintaining a desirous pumping function. Defects in structural design of the pump may cause interrupted flow of air therein.
For example, a widely used electric sphygmomanometer operated according to the principle of miniature pumping machinery based on prior art needs a check valve to be installed outside of the pump so as to prevent high pressure air from flowing back into the pump thereby causing an erroneous measurement.
In order to eliminate the imperfectness inherent to the conventional technique as mentioned above, the present inventor has designed a miniature diaphragm pump of the present invention.
It is an object of the present invention to provide a miniature diaphragm pump which can guide the air to flow smoothly so as to stabilize the air output.
It is another object of the present invention to provide a miniature diaphragm pump which can eject the air through an output port uniformly and prevent the air from flowing back into the pump via flow passage.
It is still another object of the present invention to provide a miniature diaphragm pump which can operate quietly with an energy saving effect.
To achieve these and other objects, the present invention provides a miniature diaphragm comprising a motor unit, a compression portion, and an air collecting portion. The output air is ejected through an air output port provided at the air collecting portion, while an air inlet is provided at the base of the motor unit so that air inlet and air outlet are separately provided in different portions of the pump. A pair of check valves are installed at the compression portion and at the air collection portion, so that the air may flow smoothly with stabilized air amount, wherein back flow of air is prevented. A follower rod conjoined with a cross bar provided in the compression portion is inserted in an eccentric hole formed on a rotation member in the motor unit to make eccentric circular motion when the motor unit is rotated in order to compress a pair of air bags in the compression portion in alternating fashion with the cross bar to send air to the air collection portion for a quiet and energy saving operation of the pump.